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Re: Second shim
Thinking about a second shim to handle connection establishment, I've
come up with code (not running yet ;-) to do a
int connect_by_name(char *hostname, int port);
that can be implemented entirely as a library (using non-blocking
connect() calls). It returns a socket file descriptor.
One could try to apply this technique to make connect() do the same
thing, in coordination with getaddrinfo(), but that is more complex for
1. Need the coordination between getaddrinfo() and connect() somewhere -
need to store the alternate IP addresses so that connect() can find them.
2. Need to handle cases when the socket passed in to connect has already
been bound, or has had some options set.
3. It isn't transparent to the application; the application might pass
IP address B1 to the connect() call, but the connection is in fact made
to IP address B2. Thus applications might fail due to this. The
application needs to use getpeername() to find out the actual address to
which it has connected.
For by connect_by_name() and the connect() hackery, this only applies to
TCP; can't make it apply to UDP since UDP doesn't have a notion of "I
succeeded using this IP address".